Speed difference between the entities on top of the block and the moving block itself:
Entities and players will move slightly faster then the moving block below them when standing on top of it. This will not be noticable when standing on a moving block going back and forward. So you will have to use a flying machine or other contraption that moves in one direction only to reproduce this bug.
How to reproduce:
1. create a piston contraption that moves in one direction only (e.g. a flying machine.)
2. make sure there are at least 2-3 blocks in a row for the player to stand on this way the problem is better visualized.
3. Activate the contraption while standing on top of it or with an entity on top.
Current outcome:
4. Observe the player or entity slowly moving forward relative to the contraption.
4.1. option 1: The player or entity will either stop at the edge and not move forward further when they reached the edge.
4.2. option 2: The player or entity will fall off the contraption at the front.
Expected outcome:
5. The player or entity will move at the same speed as the moving block below them and their relative location will not change over time.
Different tested situations:
This happens in a singleplayer session
This happens in a multiplayer session
This happens with lan and xbox players that remotely joined the world
This happens with all or nearly all entities but its safe to assume all entities are affected.
Examples:
Player sliding of a flying machine 1
Player sliding of a flying machine 2
Player sliding of a flying machine 3
Entity sliding of a flying machine 1
Disclaimers and other info:
The other player gave me permission to use their username in the attached video.
Please note that this bug report is different even though similar ones exist. These bug reports address either parity issues, client/server desync or clipping issues. While this one is about the speed difference.
Linked issues
is duplicated by 3
relates to 2
Attachments
Comments 8
In addition to this, when the player jumps when standing on a flying machine they will be pulled back to their previous location when trying to jump, this is not always the case more like a 1/5 chance. I can imagine this happening when moving exactly when one of the two movement ticks occur. I originally thought this was related to desync issues with the server having a different location than the client, but the movement of the piston canceling player motion doesn’t sound improbable. Should I add this to the bug report or do you think this is unlikely to be related?
I think you should report the jumping issue separately. It may still occur even if the extra entity movement that causes this bug is removed.
It doesn't matter much, but I reported the jumping issue along with moving faster than moving blocks in May 2023 (this report was made in June 2023) and my report was marked as a duplicate.
Although I suppose this report has better technical wording, I don't think mine should've been marked as that since I also covered the separate issue with jumping as well.
We might be able to mark yours as additional information to this post, since it’s probably caused by the same issue, also, I never reported the jumping issue seperately in the end.
I made a new report MCPE-183495 yesterday on the jumping issue just for simplicity's sake, and also in case it does turn out to be a separate issue (Although you're probably right that it's the same).
I have studied this using particles to show entity positions on each tick, and I have noticed two things:
Entities on moving blocks get moved twice, in two successive ticks. This might be because the technical movingBlock exists for two ticks instead of one (MCPE-103544). It seems that the first movement is usually about a full block distance or the correct/expected distance, and the second movement adds about an extra 1/2 block.
Movement distance is not consistent. I believe it varies based on where the entity is positioned on the moved block before the movement, and based on direction of motion.